[Bugfix][Processor] Replace bare asserts with ValueError in DeepseekVLV2/OCR processors (#53854)

Signed-off-by: adisivaprasad <adisivaprasad@users.noreply.github.com>
Co-authored-by: adisivaprasad <adisivaprasad@users.noreply.github.com>

tests/models/multimodal/processing/test_deepseek_ocr.py

@@ -132,3 +132,27 @@ class TestDeepseekOCREmptyImagesCrop:
                     "image_size": 1024,  # Wrong! Tensor has 640
                 },
             )
+
+
+class TestDeepseekOCRInputValidation:
+    """Bare ``assert`` used to validate user input here returned HTTP 500
+    (AssertionError) instead of HTTP 400 (ValueError) and disappeared under
+    ``python -O``, silently corrupting the tokenized sequence. See #53850.
+    """
+
+    def test_mismatched_image_count_raises_value_error(self, processor):
+        """Two ``<image>`` tokens with one image must raise ValueError, not
+        AssertionError (which would yield HTTP 500 and, under ``-O``, silently
+        drop the middle text segment)."""
+        image = Image.new("RGB", (100, 100), color="red")
+        with pytest.raises(ValueError, match="does not match number of images"):
+            processor(prompt="<image> and <image>", images=[image])
+
+    def test_missing_prompt_raises_value_error(self, processor):
+        image = Image.new("RGB", (100, 100), color="red")
+        with pytest.raises(ValueError, match="prompt and images"):
+            processor(prompt=None, images=[image])
+
+    def test_missing_images_raises_value_error(self, processor):
+        with pytest.raises(ValueError, match="prompt and images"):
+            processor(prompt="<image>\nDescribe this image.", images=None)

vllm/transformers_utils/processors/deepseek_ocr.py

@@ -250,9 +250,8 @@ class DeepseekOCRProcessor(ProcessorMixin):
                 - num_image_tokens (List[int]): the number of image tokens
         """
 
-        assert prompt is not None and images is not None, (
-            "prompt and images must be used at the same time."
-        )
+        if prompt is None or images is None:
+            raise ValueError("prompt and images must be used at the same time.")
 
         sft_format = prompt
 
@@ -311,7 +310,13 @@ class DeepseekOCRProcessor(ProcessorMixin):
     ):
         """Tokenize text with <image> tags."""
 
-        assert conversation.count(self.image_token) == len(images)
+        num_image_tags = conversation.count(self.image_token)
+        if num_image_tags != len(images):
+            raise ValueError(
+                f"Number of {self.image_token!r} tokens in prompt "
+                f"({num_image_tags}) does not match number of images "
+                f"({len(images)})."
+            )
         text_splits = conversation.split(self.image_token)
         images_list, images_crop_list, images_seq_mask, images_spatial_crop = (
             [],

vllm/transformers_utils/processors/deepseek_vl2.py

@@ -203,9 +203,8 @@ class DeepseekVLV2Processor(ProcessorMixin):
                 - num_image_tokens (list[int]): the number of image tokens
         """
 
-        assert prompt is not None and images is not None, (
-            "prompt and images must be used at the same time."
-        )
+        if prompt is None or images is None:
+            raise ValueError("prompt and images must be used at the same time.")
 
         sft_format = prompt
         (
@@ -310,7 +309,13 @@ class DeepseekVLV2Processor(ProcessorMixin):
         cropping: bool = True,
     ):
         """Tokenize text with <image> tags."""
-        assert conversation.count(self.image_token) == len(images)
+        num_image_tags = conversation.count(self.image_token)
+        if num_image_tags != len(images):
+            raise ValueError(
+                f"Number of {self.image_token!r} tokens in prompt "
+                f"({num_image_tags}) does not match number of images "
+                f"({len(images)})."
+            )
         text_splits = conversation.split(self.image_token)
         images_list, images_seq_mask, images_spatial_crop = [], [], []
         num_image_tokens = []